High electrochemical performance of a disordered 3.9V-LiFeSO4F for Lithium ion battery

Byoungwoo Kang

Department of Materials Science and Engineering at POSTECH 

Abstract: Rechargeable Li ion batteries are widely used as power sources for portable electric and electronic devices. Recently, use of Li ion batteries has been extended to large-scale applications such as electrical vehicles and energy storage systems. In these large scale applications, the energy density and safety of the battery as well as low cost are important. Especially, LiFePO4 has been attracted a lot of attention because of excellent capacity retention with very high rate capability. However, LiFePO4 has a low operating voltage leading to relatively low energy density. Efforts to increase the operating voltage of polyanion-based compounds have been tried by exploiting an inductive effect. LiFeSO4F achieves the highest voltage (3.9 V) among Fe2+/Fe3+ redox couples, and therefore can have higher energy density than LiFePO4. However, full utilization of 3.9V-LiFeSO4F is severely limited by its non-scalable synthesis process and poor electrochemical activity that originates from full disordering of Li/Fe in metal sites.

In this talk, I will discuss about how experimental parameters affect the stability 3.9V-LiFeSO4F in simple solid-state reaction process and the electrochemical properties of LiFeSO4F even though the compound has severe structural disadvantages for facile kinetic property. Furthermore, I will show that the disordered 3.9V-LiFeSO4F can be very promising cathode material with respect to volumetric changes during charging/discharging and rate capability.



• 2009. Ph. D, Massachusetts Institute of Technology (MIT), Boston, USA  

   Thesis: “Designing materials for energy storage with high power and high energy density: LiFePO4 cathode material” 

•  2003. B.S., Seoul National University, Seoul, Korea                                                            

Professional Experiences

•  2015.09 ~ present, Associate Professor, MSE, POSTECH

•  2011.8 ~ 2015.08, Assistant Professor, MSE, POSTECH

•  2009 ~ 2011.7, Postdoctoral Associate, DMSE, MIT

•  2003.01 ~ 2003.08, Student Researcher, Seoul National University

Research Interests

  •  Developing advanced materials for energy storage technologies such as lithium ion batteries and sodium ion batteries

  •  Designing novel materials for next generation energy storage technologies

  •  Designing solid-electrolytes for all solid-state batteries and developing all solid-state battery 

Publications (Selected)

1) B. Kang and G. Ceder, Battery materials for ultrafast charging and discharging, Nature, 458, p.190 ~ p.193 (2009). (# of Citation: 1895, From March 2009 ~ present (2017.08.10))

2) Junghwa Lee, Nicolas Dupre, Maxim Avdeev and B. Kang, "Understanding the cation ordering transition in high-voltage spinel LiNi0.5Mn1.5O4 by doping Li instead of Ni ", Scientific Reports, (2017)

3) Minkyung Kim, Seongsu Lee and B. Kang, "High energy density polyanion electrode material; LiVPO4O1-xFx (x 0.25) with tavorite structure ", Chemistry of Materials, 29(11), 4690-4699 (2017)

4) Minkyu Kim and B. Kang, "Highly-pure tiplite 3.9V-LiFeSO4F Synthesized by a single-step solid-state process and its high electrochemical performance", Electrochimica Acta, 228, 160-166 (2017)

5) Heetaek Park1, Keeyoung Jung, Marjan Nezafati, and Changsoo Kim, and B. Kang, "Sodium Ion Diffusion in Nasicon (Na3Zr2Si2PO12) Solid Electrolytes : Effects of Excess Sodium", ACS Applied Materials & Interfaces, 8(41), 27814-27824  (2016)

6) Jangwook Lee and B. Kang, "Superior electrochemical performance of N-doped nanocrystalline FeF3/C with single-step solid-state process ", Chem. Comm, 52, 12100-12103 (2016)

7) Yongjo Jung and B. Kang, "Understanding abnormal potential behaviors at 1st charge in Li2S cathode material for rechargeable Li-S battery ", Physical Chemistry Chemical Physics, 18, 21500-21507 (2016)

8) Minkyung Kim, Seongsu Lee, and B. Kang,"Fast rate capable electrode material with higher energy density than LiFePO4:4.2V LiVPO4F synthesized by scalable single-step solid-state reaction", Advanced Science, (2015) (Invited paper)

9) J. Lee, C. Kim and B.Kang, "High electrochemical performance of high voltage LiNi0.5Mn1.5O4 by decoupling the Ni/Mn disordering from the presence of Mn3+ ions", NPG Asia Materials, 7, e211 (2015)

10) M. Kim, Y. Jung, B. Kang, "High electrochemical performance of 3.9 V LiFeSO4F directly synthesized by a scalable solid- state reaction within 1 h", Journal of Materials Chemistry A, 3, 7583-7590 (2015)